Piano tonal apparatus



Sept. 28, 1965 w. H. BENDALL 3,208,325

PIANO TONAL APPARATUS Filed July 12, 1965 Q Q 0 Q W *r-*-- 2%:

United States Patent 3,208,325 PIANO TONAL APPARATUS Wilfrid H. Bendall, P.O. Box 126, Stonington, Conn. Filed July 12, 1963, Ser. No. 294,722 7 Claims. (Cl. 84-184) This invention relates to piano tonal apparatus as an integrated assembly adapted for installation in finished piano cases of either horizontal or vertical form. It is disclosed and described herein as installed in the horizontal form by way of example only, its alternative installation in the vertical form being readily ascertainable therefrom.

By virtue of a wide tonal range and as the essential means to interpretation of an enduring literature, the piano is established as a musical instrument of unique cultural importance. An empirical design basis and uneconomic construction, however, appear to have limited production of tonally superior instruments to a small fraction of the number that could satisfy the potential demand for it. In its ultimate tonal development, as exemplified in the large grand pianos, the instruments cost, weight and bulk continues to place it increasingly beyond the reach of musically perceptive persons needing instruments of such quality. The piano industry has for years sought to meet this need by producing more compact, lower priced instruments, but it is tacitly acknowledged that, tonally, the present small instruments still leave much to be desired. The diificulty appears to be grounded in adherence to traditional design and construction methods, which are believed to be essential to production of the characteristic piano tone. Efforts to develop improved small pianos invariably seek to do so by sealing down the proportions of the large instruments. There are practical limits to this precedure and such scaling down as can be accomplished does not appear to ensure an economic or musically acceptable solution.

The essential tone-production components of the classical piano comprise its string frame, tensioned strings and soundboard. These constitute the tonal heart of the instrument independently of its casing and key action. Hence, the critical need in the art is for an integrated and easily manufactured assemblage of these components, preferably in a form facilitating design modifications and permitting a broad choice of materials of construction. This would enable piano makers to arrive at piano tone characteristics equal or superior to those of the large grand pianos at negligible cost in research and development time. To meet this need by providing an eflicient, simply constructed, unitary piano tonal apparatus, is thus a broad object of the present invention.

Other equally important objects are to provide such tonal apparatus within compact instrumental dimensions and in a structure of substantially lower total weight and manufacturing cost; and to provide such apparatus in a permanently tuned and thus tonally stable condition, conveniently adapted for removable installation in finished piano cases of either horizontal or vertical form.

The structural features necessary to accomplish the foregoing objectives are set forth in the following specification and accompanying drawings in which,

FIGURE 1 is a partly diagrammatic plan view of the piano tonal apparatus of this invention, showing it installed in a horizontally disposed piano case.

FIGURE 2 is a fragmentary front elevation on a larger scale, viewed on the plane 22 of FIG. 1.

FIGURE 3 is a fragmentary vertical cross-sectional view on the line 3-3 of FIG. 1.

FIGURE 4 is a fragmentary vertical section on the line 44 of FIG. 1 showing the interconnection of string and soundboard components.

3,208,325 Patented Sept. 28, 1965 FIGURE 5 is a plan view of the parts shown in FIG. 4.

As is well known to those skilled in the art, it is customary to provide pianos with a massive iron frame to withstand the pull of some 230 or more strings, totalling as much as thirty tons in the large grands. The strings are attached to the frame with the terminal points of their active lengths slightly lower than their hearing on the bridges of the soundboard, the resulting string downbearing thereon being relied upon to maintain effective contact between strings and board. This traditional construction, though ideally simple in principle, compels use of a relatively rigid and heavy structural assembly with inherently limited tuning and tonal stability. A further difficulty results from the design practice of overstringing to obtain greater bass string lengths, necessitating a divided string scale and soundboard bridge and imposing structural discontinuities at a tonally critical part of the assembly. The incidental requirement for sixty or more three-string unisons in these instruments, to obtain greater sound output, may also be considered as imposed by the disproportionate weight and rigidity of the structure.

The tonal apparatus of the present invention avoids these'difiiculties by eliminating the traditional design features of downbearing and overstringing, reducing the relative mass and number of strings while retaining adequate bass string lengths. This permits use of a substantially lighter and smaller string frame, with positive string tensioning means, and a more responsive string bridge and soundboard structure. It is to be understood that piano cases utilizing this apparatus may have any desired external style applicable to the broadly designated horizontal .and vertical case styles. Its ready adaptability to both of these styles constitutes a unique and useful economic feature. In the drawings herewith it is shown as applied to a horizontal case of rectangular plan form, the alternative application to the currently more familiar vertical or upright style, which is also essentially rectangular in plan form, will be readily apparent therefrom. It should also be noted that only those parts of the case are shown to which the apparatus is attached. I

In FIGS. 1-3 reference numeral 10 designates a horizontally disposed piano case having Vertical back panel 11, vertical side panels 12 and 13, and a bottom panel 14 largely cut away as indicated by the dotted outline 15 in FIG. 1. An uncut front portion (not shown) of this bottom panel may be projected forward with side panels 12 and 13 to any desired extent to provide a base for the usual keyboard and action mechanism. Placed within and removably attached to the case by brackets 16, 17, 18 and 19 is the string frame 20, of trapezoidal outline, constructed or rolled or extruded metal angles 'which may be either bolted or welded together or, alternatively, the frame may be an integral casting of any suitable metal. This string frame further comprises primary frame members 21, 22 and 23 have rounded edge three of its sides, and secondary structural members 24, 25 and 26 bracing the primary members in the line of the string tensional load. As shown in FIG. 3 the primary frame members 21, 22 and 23 have rounded edge portions 27 shaped to provide coplanar string alignment and bearing lines, frame members 21 and 22 being further provided with hitch pins 28 for attachment .of the looped string ends, and frame memb.er,23 with a projecting shoulder 29 holding string tensioning means. The latter comprise threaded tuning screws 30 engaging threaded block members 31 having cross pins 32 for attachment of looped ends 33 of string unisons 34.

For clarity in the drawings, certain only of the string unisons, designated by reference numerals 34 and 36 are shown, to indicate their general arrangement. A substantial economic advantage of the tonal apparatus disclosed herein is attained by using a single string tensioning means to tune plural string unisons for each note so that only 88 tuning centers are required as compared with some 230 or more in pianos of current manufacture. The

plural string unisons 34 are arranged thus throughout the usual eighty-eight note compass with the exception of a few single string unisons 36, in the extreme bass section, where the required string mass results in string diameters greater than can be accommodated with desirable lateral clearance using plural strings. Each unison comprises a straight, coplanar and precisely defined active string length extending from the bearing shoulder 27 on frame members 21 and 22 to triangular bearing blocks 37. These bearing blocks may be bonded, welded or pinned to the frame member 23, each block having a bearing edge 38 arranged substantially at right angles to the string axis of each unison and positioned as required by the usual -strike proportion relative to the specified hammer strike line diagrammatically indicated by the dot and dash line 3939 extending across FIG. 1. Similarly it .will be understood that the speakinglength of each unison is the string portion extending between the bearing blocks 37 and the attachment to the string bridge and soundboards, hereinafter described.

On further reference to FIGS. 2 and 3 it will be observed that the looped end portions of the strings of each unison are turned normal to the string axis at the bearing shoulders 27 for attachment to hitch pins 28 and to tuning ,block cross pins 32 at their respective terminal positions. This arrangement permits maximum working string lengths within given frame dimensions and also facilitates use of screw-threaded tensioning means to ensure mechanically positive tuning. As is well known, the usual frictionally held tuning pins are not mechanically positive and slip continuously in response to playing forces and atmospheric changes. It is instructive to note, however, that screw-tensioned tuning, in principle, was used many years ago by a well known piano firm and was subsequently abandoned as impracticable. The present invention makes new and effective use of the screw-tuning principle by pro- .viding coplanar and collinear string working lengths in self-contained bearing connection with coplanar string bridging means and with a flat, resiliently mounted soundboard in substantial parallelism with the strings.

Reference numeral 40 in FIGS. 1 and 3 designates the continuous string bridging means. As shown, it may conveniently comprise a pair of parallel wires curved into conformity with the computed location of sound-post elements 41 which connect the string unisons and bridging means to the soundboard 42. The string bridging means are securely interconnected with the strings, sound-posts and soundboard by the self-contained pressure of the locknut and bearing washer assemblies 43 at the string connection ends of the sound-posts and by the headed fastener and bearing washer assemblies 44 at the soundboard connection. As disclosed in larger detail in FIGS. 4 and 5,

the string bridging wires 40 are aligned on each side of the sound-posts and the fastening means extends between them and between the paired strings of the unisons 34 at each such position. This ensures a-' balanced, self-contained contact pressure between the parts and effective transmission of the vibratory motion of the strings to the soundboard for the production of piano tone. At the single string bass unisons 36, the above described interconnection of the parts is accomplished by locating the sound-posts between adjacent unisons. It should be noted that While such fastening means are required at each paired string unison and bridge connection, the soundposts may be spaced two or more unisons apart, thus at least halving the required number of such assemblies.

The soundboard 42 is indicated in the drawings as of substantial relative thickness, but it may alternatively comprise a relatively thin tensioned sheet of any suitable material. As shown, the soundboard is of rectangular shape and is installed with its oppositely disposed, narrower width edge portions 42A and 42B screwed to fillets or ledges 43 secured to the side panels 12 and 13 of the case and its oppositely disposed longer edge portions 42C and 42D free from contact therewith. This freedom of the longer edge portions is found to be desirable for proper amplitude of the soundboard in producing tone.

It was observed earlier, herein, that the adaptability of the tonal apparatus of this invention to installation in either horizontally or vertically disposed piano cases is an important and useful economic feature. Such adapt ability is accomplished in the vertical style by arranging "it with the primary frame member 23 at the top, in which event the soundboard will be in front and the case can be enclosed at the back in any desired manner (preferably with tonal apertures). Alternatively, the sound-posts and soundboard can be located at the back of a string frame so erected, in which event the sound-posts will be made long enough to clear the secondary frame members 24, 25 and 26. It will be observed that the string, bridge and sound-post connection points, with the exception of the short lengths of bridge directly under frame members 25 and 26, are accessible from both sides of the string frame for this purpose. In manufacture it will be convenient to provide sound-posts with a standard length, enabling attachment of the soundboard on either side of the string frame without changing the dimensions of any part. In both horizontal and vertical arrangements the usual piano hammers act on the strike line 39-39 through the space immediately in front of the soundboard edge 42D. In the vertical arrangement, with the soundboard transferred to the back, the soundboard may be made slightly wider and its free edge 42D extended to within close clearance of the interior of the piano case at the top of the instrument.

While this invention has been disclosed and described largely in terms of a particular embodiment by way of example, no limitation to such embodiment is conveyed thereby or to any modification coming within the scope of the appended claims.

I claim:

1. Piano tonal apparatus adapted for installation in a piano case, said apparatus comprising a string frame having a plurality of string unisons and a soundboard, said string frame having edge portions shaped to hold string tensioning means and provide coplanar string bearing lines, each of said string unisons comprising a plurality of string elements having end portions turned normal to the axes thereof at said bearing lines and each held in simultaneously tuned relationship by a common tensioning means, said unisons being interconnected in the plane thereof by a continuous resilient string bridge member and connected to said soundboard by a plurality of soundposts extending normal thereto, said soundboard being substantially rectangular in outline and having oppositely disposed edge portions secured to said case and oppositely disposed edge portions free from attachment thereto.

2. The piano tonal apparatus of claim 1 wherein said bridge member further comprises resilient elements intersecting said string elements and having fastening means at said intersection.

3. The piano tonal apparatus of claim 1 wherein said tensioning means comprise block members having a screwthreaded end portion adapted to receive screw tensioning means and a slotted end portion having a cross-pin adapted to engage said string elements.

4. The piano tonal apparatus of claim 1, said string frame being constructed and arranged to enable attachment of said bridge member, said sound-posts and said soundboard to either side thereof.

5. Piano tonal apparatus comprising a string frame: having tensioned string unisons and a soundboard con-- nected thereto, said string frame having tensioning and alignment means holding said string tmisons in collinear and coplanarly spaced relationship, said string unisons comprising a plurality of string elements each tuned by a common tensioning means and interconnected for coincident vibratory motion by a resilient bridge member each of said string unisons being secured thereto by a common fastening means and having means extending normal thereto to transmit said vibratory motion to the soundboard.

6. The piano tonal apparatus of claim 5, said soundboard being flat and in substantial parallelism with said string unisons.

7. Piano tonal apparatus adapted for installation in piano cases of either horizontal or vertical form, said apparatus comprising a string frame, multiple string unisons attached thereto, each said unison having unitary tensioning means, string bridging means intersecting said unisons and having fastening means at said intersection points,

References Cited by the Examiner UNITED STATES PATENTS 57,743 9/ 66 Martins 84-185 594,325 11/97 Christie 84-185 852,917 5/07 Wells 84-192 X 1,432,338 :10/221 Johnston 84-192 FOREIGN PATENTS 587,051 11/59 Canada.

LEO SMILOW, Primary Examiner. 

1. PIANO TONAL APPARATUS ADAPTED FOR INSTALLATION IN A PIANO CASE, SAID APPARATUS COMPRISING A STRING FRAME HAVING A PLURALITY OF STRING UNISONS AND A SOUNDBOARD, SAID STRING FRAME HAVING EDGE PORTIONS SHAPED TO HOLD STRING TENSIONING MEANS AND PROVIDE COPLANAR STRING BEARING LINES, EACH OF SAID STRING UNISONS COMPRISING A PLURALITY OF STRING ELEMENTS HAVING END PORTIONS TURNED NORMAL TO THE AXES THEREOF AT SAID BEARING LINES AND EACH HELD IN SIMULTANEOUSLY TUNED RELATIONSHIP BY A COMMON TENSIONING MEANS, SAID UNISONS BEING INTERCONNECTED IN THE PLANE THEREOF BY A CONTINUOUS RESILIENT STRING BRIDGE MEMBER AND CONNECTED TO SAID SOUNDBOARD BY A PLURALITY OF SOUNDPOSTS EXTENDING NORMAL THERETO, SAID SOUNDBOARD BEING SUBSTANTIALLY RECTANGULAR IN OUTLINE AND HAVING OPPOSITELY DISPOSED EDGE PORTIONS SECURED TO SAID CASE AND OPPOSITELY DISPOSED EDGE PORTIONS FREE FROM ATTACHMENT THERETO. 